Engine starter



June 17, 1930. w. MCGRnH 1,764,027

ENGINE STARTER Original Filed Aug. 18, 1.922

Ira/6725b?" itatented dune 17, T1936 rattan WILLIAM L. IIIGGRATE, F ELEVIIRA, NEW YORK, ASSIGNOR T0 ECLIPSE MACHINE CQM- EANY, 0Tb ELTEKIRA, NEW YORK, A CQRIPOMTION 015 NEW YORK ENGINE fsrnn'rnn Application filed August 18, 1922, Serial No. 582,668. Renewed. January 19, 19%7.

My invention relates to engine starters and to that part thereof known as the drive or transmission, and the object thereof is to provide the drive with means for protecting the usual drive spring against abnormal torque loads. Speaking in general terms, such means consist of the provision of an automatic disengageable clutch cooperating with the drive spring, whereby such spring is utilized in protecting itself'against such loads. In ractice, the drive spring which is a coiled sprmgo'f the torsion and compression type, normally holds the clutch members in full engagement but yields compressively dur-.

ing the automatic disengaging or uncoupling of the clutch as a result of the torque load bein transmitted through the clutch.

in the drawing, Fig. 1 is an elevation of a drive, partly in section, embodying my invention; Fig. 2 a similar view but showing the position of the parts with the clutch members declutched; Fig. 3 an elevation of the inner clutch member or driving head and Figs. 4 and 5 perspectives of the two clutch members.

For the sake of a clear and definite description of my invention, I have shown and will hereinafter describe the same as embodied in a well-known form of drive of the general construction shown in Bendix Patent No. 1,125,935 issued on J anuary, 26th, 1915, and with some particulars of construction according to my Patent No. 1,591,987, issued on January 13, 1926, but it will be understood that my invention, in its broader aspect, is not limited to such specific construction and that it may be embodied in structures of drives of different character. It will also be understood that my invention is equally applicable to a drive of the out-board type as distinguished from the in-board type herein illustrated.

Referring to the embodiment of my invention as shown inthe drawing, the electric starting motor 1 has an extended armature shaft 2 onwhichismountedthe hollow screw shaft 3. On this screw shaft is threaded a pinion 4 adapted for longitudinal movement along the screw shaft for engagement with the usual fly wheel 5, and for rotary movement with such shaft for rotating the flywheel. The drive is provided with a driving head made in two parts, the first one of which.

marked 6 is secured in suitable'manner to the armature shaft as by means of the transversepin 7 and the key 8. The second part marked 9 of this head is loosely mounted on the armature shaft for rotar movement with respect thereto and for ongltudinal movement thereon. These two parts of the driving head. constitute clutch members provided with the complementary clutch jaws 10 and 11 whose engaging faces, instead of being perpendicular to the direction of pressure, are inclined at an angle thereto with the result that the pressure due to torque tends to separate the jaws and eventually cause them to disengage as shown in Fig. 2.

The clutch member or driving head 9 is operatively connected with the driven head 12 of the screw shaft by means of the coiled drive spring 13 through the medium of the screws 14 and 15 which screw through eyes at the opposite ends of the springs and into the heads 9 and 12. This spring is a torsion and a compression spring and the drive is assembled with the spring under slight compression and with the coils open as seen in Fig. 1. Inasmuch as the head 9 is loosely mounted upon the armature shaft the expansion action of the spring normally holds the clutch jaws in full engagement and restricts the separation of the clutch jaws caused by the longitudinal pressure of the drive spring, so that with a given longitudinal resistance the clutch will carry a given or predetermined torque dependent upon the angle on the face of said aws. When this degree of torque is reached or exceeded, the clutch jaws will automatically disengage or become declutched by the longitudinal inward motement of the head 9 against the expansion pressure of the drive spring, the parts then taking the position shown in Fi 2. The head 6 will thereupon rotate free y without transmitting any torque to the head 9. When in this rotation of the head 6 the jaws come again in register, the spring 13 will thrust the head 9 longitudinally into engagemeat with the head 6, and if the excess ve resistance to the pinion continues, said au-. tomatic declutching and clutching will likewise continue. When such excessive resistance ceases, the clutch jaws will be in engagement and capable of transmitting the normal torque. In this manner and by these sion of the spring but adapted to be automaticallydeclutched when a predetermined degree of torque is reached.

her mounted on the latter shaft, a

2. An engine starter drive including a driving shaft, a hollow screw shaft mounted thereon, a driving member threaded onto the screw shaft, a driving head loosely mounted? on the driving shaft, and a coiled drive spring operatively connecting the head and screw shaft, said driving shaft and head having complementary clutch jaws normally held in engagement by the expansion of the spring. I

3. n on ine starter drive including a driving shai' t, a driven shaft, a drivin mem-- riving head loosely mounted on the driving ,shaft, and a coiled drive spring connected respectively with the driven shaft and with the driving head, said driving shaft and driving head aving complementary clutch-jaws normally held in engagement by the expansion of the spring and said jaws having engaging faces inclined at an angle to the direction of pressure whereby they will be automatically declutched when a predetermined degree of torque is reached.

4. An engine starter drive including a driving shaft, a driven shaft, a driving member mounted on the latter shaft, and driving connections between the two shafts includin a coiled drive spring and a clutch in which driving relation is normally held established by the longitudinal pressure of said spring but which is adapted to be automatically declutched to break such driving relation when a predetermined degree of torque is reached.

5. An engine starter drive including a driving shaft, a driven shaft, a drivin member mounted on the latter shaft, a driving head loosely mounted on the driving shaft, a coiled drive spring connected respectively with the driven shaft and with the driving head, and a clutch constituting the driving: ,connection between said driving shaft and driving head and acted upon by the longitudinal pressure of said spring to normally establish driving relation between said shafts but adapted to be automatically declutched to break said driving" relation when a predetermined degree of torque 1s reached.

6. An engine starter drive including a driving element, a driven shaft member, a driving member mounted on said shaft .for rotary movement therewith and longitudinal movement thereof into engagement with a member of the engine to be started, and a driving connection between said element and said shaft including a drive spring and a clutch in which driving relation is normally held established by pressure of said spring but which is adapted to be automatically declutched against the resistance of said spring to break such driving relation when a predetermined degree of torque is reached.

7. An engine starter drive including a driving element, a driven member in the form' of a screw shaft, a driving member threaded on said shaft for rotary movement therewith and longitudinal movement thereof into engagement with a member of the engine to be started, and a driving connection between said element and said shaftincluding a drive spring and a clutch, said sprin andclutch normally coo crating to establis driving relation, said c utch'being adapted to be automatically de-clutched against resistance of said spring to break such driving relation .when a predetermined degree of torque is reached.-

.8. An engine starter drive including a driving element, a driven member in the form of a screw shaft, a driving member threaded on said shaft for rotary movement therewith and longitudinal movement thereof into engagement with a member of the engine to be started, and a drivin said element and said s aft including a drive spring and a clutch, said clutch comprising complementary Ijawsidisposed on said ele'-- ment and said shaft and normally held in engagement by said spring,'said jaws being arranged to be automatically de-clutched against resistance of said spring when a predetermined degree of torque is reached.

connection between i 9. An engine starter drive including a driving member adapted to engagea member of an engine to be started, an axially movable driven shaft associated with said driving member to rotate'it, a driving element, and a combined driving-spring and clutch-structure operatively associating said driving ele- I ment and said driven shaft for permitting axial yielding of said driven shaft and for a torque transmission through said clutch and spring and comprising a clutch held nor-' mally in engagement by the tension of said spring and adapted to be automatically declutched against the tension of said spring.

10. An engine starter drive including a driving member adapted to engage a member of an engine to be started, an axially movable driven shaft associated with said driving member to rotate it, a driving element, and a combined driving-springnnd clutch-strum, ture operatively associating said driving element and said driven shaft for torque transmission through said clutch and spring and comprising a spring yieldingly positioning said driven shaft against axial movement and a clutch inherently tending to de-clutch un der torque and normally held against reclutching by tension of said spring.

11. An engine starter drive including a driving member adapted to engagea member of an engine to be started, an axially movable driven shaft associated with said driving member to rotate it, an axially fixed driving element, and a combined driving-spring and clutch-structure operatively associating said driving element and said driven shaft for torque transmission through said clutch and spring and comprising a spring yicldingly positioning said driven shaft against axial movement and a clutch inherently tending to de-clutch under torque and having an element, movable for de-clutching, connected with said spring and normally held against de-clutching by tension of said spring.

WILLIAM L. MoGR-ATH. 

